My invention pertains to apparatus for driving in the ground post-holes adapted to receive conventional posts of various materials such as precast concrete and of a configuration and composition not adaptable to being directly driven into the ground.
Posts that are driven into the ground are limited in bearing area by the size of the post and the depth to which they are driven. Posts that are set in previously prepared holes are adapted to have their effective bearing area increased either through the use of concrete or loose aggregate tamped firmly between the post and the ground. Such holes normally are dug either manually or by power-driven augers mounted on a vehicle. Both methods result in the production of loose material which, if used to fill the space between the post and the hole wall, results in the bearing area limitation referred to in connection with driven posts. Alternatively, it is necessary to remove the loose material from the site.
A need exists for apparatus readily adapted to the terrain which will rapidly dig post holes of a size larger than the post.
Typical prior art pertains to post drivers, rather than to post-hole drivers. A post driver using a fluid cylinder to raise a driving weight in which the weight returns the piston to its original position is shown in U.S. Pat. No. 2,940,267 to Shaver and U.S. Pat. No. 2,659,583 to Dorkins. The patent to Welsch et al U.S. Pat. No. 3,961,672 discloses lateral and fore-and-aft positioning of an impact hammer relative to a support.
However, presently available post-hole apparatus is cumbersome to position and align in the fore-and-aft, lateral and vertical positions, resulting in a tedious and costly operation. There is a need for post-hole driving apparatus that is easily attached and removed from the support vehicle. Such post-hole driving apparatus must be capable of rapid locating and alignment without the need for precision positioning of the vehicle. The post-hole driving apparatus must drive a vertical post-hole with the support vehicle on sloping terrain. The post-hole driver must be free of damage by engagement with subterranean objects. It is the general object of this invention to provide apparatus which may be rapidly positioned and which will produce vertical post-holes.
Another object of the invention is to provide post-hole driving apparatus that is readily attached to and removed from conventional vehicle equipment.
Another object of the invention is to provide post-hole driving apparatus that permits precision positioning of the post-hole driver without the need for precise positioning of the support vehicle.
Another object of the invention is to provide post-hole driving apparatus that will drive a vertical hole with the support vehicle on sloping terrain.
Another object of the invention is to provide post-hole driving apparatus that assures the driving of a vertical hole.
Another object of the invention is to provide post-hole driving apparatus which in use will not be damaged by contact with rocks and other subterranean objects.
Another object of the invention is to provide post-hole driving apparatus that is easily removed from the finished hole.
Another object of the invention is to provide post-hole driving apparatus that drives a hole providing for increased post-bearing area on the ground.
Another object of the invention is to provide post-hole driving apparatus that produces a tapered hole.
Another object of the invention is to provide post-hole driving apparatus in which the drive hammer is cycled automatically.
Broadly considered, the foregoing and other objects of this invention are accomplished by pivotally mounting a frame on the drawbar of a vehicle with the frame supported in a fore-and-aft position by a fluid cylinder connecting the frame to the vehicle. A second fluid cylinder provides for pivotal positioning of the frame relative to the vehicle drawbar, thereby moving the free or outboard end of the frame transversely. The frame is provided at its outboard end with a pivotally mounted yoke having the pivots transverse to the frame providing for fore-and-aft pivoting of the yoke.
Pivotally mounted on the yoke is a bearing through which the support shaft for the post-hole bit assembly is slideably positioned and adapted to be locked in a raised position. The pivotally mounted yoke and the pivotally mounted bearing are dampened against rapid movement by shock absorber means. The post-hole bit together with a drive hammer are an integral part of an assembly which includes a slide guide for the drive hammer. Mounted within the driving bit is a single-acting cylinder and piston which raises the drive hammer and, upon release of the fluid pressure, permits the hammer to drop, driving the bit into the ground.
These and other objects of the invention are achieved by the construction arrangement illustrated in the accompanying drawings and described herein.